Probing the different chaperone activities of the bacterial HSP70-HSP40 system using a thermolabile luciferase substrate.

Détails

ID Serval
serval:BIB_4ABCBE29AAF5
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Probing the different chaperone activities of the bacterial HSP70-HSP40 system using a thermolabile luciferase substrate.
Périodique
Proteins
Auteur(s)
Sharma S.K., De Los Rios P., Goloubinoff P.
ISSN
1097-0134 (Electronic)
ISSN-L
0887-3585
Statut éditorial
Publié
Date de publication
2011
Volume
79
Numéro
6
Pages
1991-1998
Langue
anglais
Résumé
During mild heat-stress, a native thermolabile polypeptide may partially unfold and transiently expose water-avoiding hydrophobic segments that readily tend to associate into a stable misfolded species, rich in intra-molecular non-native beta-sheet structures. When the concentration of the heat-unfolded intermediates is elevated, the exposed hydrophobic segments tend to associate with other molecules into large stable insoluble complexes, also called "aggregates." In mammalian cells, stress- and mutation-induced protein misfolding and aggregation may cause degenerative diseases and aging. Young cells, however, effectively counteract toxic protein misfolding with a potent network of molecular chaperones that bind hydrophobic surfaces and actively unfold otherwise stable misfolded and aggregated polypeptides. Here, we followed the behavior of a purified, initially mostly native thermolabile luciferase mutant, in the presence or absence of the Escherichia coli DnaK-DnaJ-GrpE chaperones and/or of ATP, at 22 °C or under mild heat-stress. We concomitantly measured luciferase enzymatic activity, Thioflavin-T fluorescence, and light-scattering to assess the effects of temperature and chaperones on the formation, respectively, of native, unfolded, misfolded, and/or of aggregated species. During mild heat-denaturation, DnaK-DnaJ-GrpE+ATP best maintained, although transiently, high luciferase activity and best prevented heat-induced misfolding and aggregation. In contrast, the ATP-less DnaK and DnaJ did not maintain optimal luciferase activity and were less effective at preventing luciferase misfolding and aggregation. We present a model accounting for the experimental data, where native, unfolded, misfolded, and aggregated species spontaneously inter-convert, and in which DnaK-DnaJ-GrpE+ATP specifically convert stable misfolded species into unstable unfolded intermediates.
Mots-clé
Adenosine Triphosphatases/metabolism, Animals, Escherichia coli/metabolism, Escherichia coli Proteins/metabolism, Fireflies/genetics, Fireflies/metabolism, HSP40 Heat-Shock Proteins/metabolism, HSP70 Heat-Shock Proteins/metabolism, Heat-Shock Proteins/metabolism, Hot Temperature, Luciferases/genetics, Luciferases/isolation & purification, Mutation, Protein Folding, Protein Stability
Pubmed
Web of science
Création de la notice
18/05/2011 10:34
Dernière modification de la notice
20/08/2019 14:58
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